Rat poison can kill squirrels because they are both rodents with similar physiology, but this practice is highly discouraged and dangerous. Using rodenticides for squirrel control introduces severe risks to pets, wildlife, and the environment. Furthermore, using most commercial rodenticides against squirrels is illegal because they are not listed as a target pest on the product’s label. For these reasons, wildlife experts strongly recommend non-lethal management methods.
The Effectiveness of Rodenticides on Squirrels
Rodenticides, particularly anticoagulant rodenticides (ARs), are designed to work across the order Rodentia, which includes squirrels. These poisons inhibit the enzyme necessary for recycling Vitamin K in the liver, a substance required for producing blood clotting factors. When the animal consumes a toxic dose, its blood loses the ability to coagulate, leading to fatal internal bleeding over several days.
The toxicity varies depending on the specific chemical formulation. First-generation anticoagulants, such as warfarin, typically require the squirrel to consume the bait multiple times over several days to ingest a lethal amount. Second-generation anticoagulants (SGARs), including brodifacoum and bromadiolone, are significantly more potent and can deliver a lethal dose after a single feeding. SGARs remain active in the animal’s system longer, increasing the danger to other animals in the food chain.
Understanding Secondary Poisoning Hazards
The most serious consequence of using rodenticides is the risk of secondary poisoning, also called relay toxicity, which affects non-target animals. After ingesting the poison, the squirrel becomes slow, weak, and disoriented over several days, making it easy prey. When a predator or scavenger consumes the poisoned carcass, the stored toxins are transferred to the new animal.
This process poses a direct threat to domestic pets, such as dogs and cats, which may hunt a sick squirrel or scavenge its body. It also impacts native wildlife, including birds of prey like hawks and owls, and mammalian predators like foxes and coyotes, causing the poison to move up the food chain. Symptoms of secondary poisoning in non-target species are similar to the primary poisoning effects: uncontrolled internal bleeding, which can manifest as lethargy, bruising, or blood in the urine or feces. The long half-life of second-generation anticoagulants means that small, repeated exposures can accumulate to a fatal dose in a predator.
Legal Restrictions on Using Rat Poison for Squirrels
The use of any pesticide in the United States is regulated by the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), administered by the Environmental Protection Agency (EPA). Under FIFRA, the product label is considered federal law, and any application inconsistent with the instructions is a violation. Since most commercial rat and mouse poisons do not list squirrels as a target species, using them for squirrel control is illegal.
Pesticide manufacturers must register their products with the EPA, proving the product will not cause “unreasonable adverse effects on the environment” when used as directed. Because squirrels are considered wildlife and not structural pests, most product registrations exclude them to limit the risk of non-target animal exposure. Violations of FIFRA can result in civil or criminal penalties, underscoring the importance of strictly following the label instructions.
Non-Lethal Squirrel Management Alternatives
Effective, long-term squirrel management focuses on exclusion and habitat modification rather than lethal methods. Exclusion involves sealing all potential entry points into structures using durable, gnaw-proof materials. For common access points like attic vents, chimneys, and gaps along the roofline, heavy-duty galvanized hardware cloth is recommended. The mesh size of this metal screening should be no larger than one-half inch to prevent squirrels from squeezing through.
Habitat modification centers on removing sources of food and shelter that attract squirrels to the area. This includes trimming tree branches at least six feet away from the house to eliminate jump-off points to the roof. Securing garbage cans, cleaning up fallen nuts or fruits, and using squirrel-proof bird feeders removes primary food incentives. For existing infestations, licensed wildlife control professionals can use humane traps and one-way doors to evict the animals, followed by permanent exclusion repairs.